International audienceThe aim of this paper is to introduce the WIRCam Ultra Deep Survey (WUDS), a near-IR photometric survey carried out at the CFH Telescope in the field of the CFHTLS-D3 field (Groth Strip). WUDS includes four near-IR bands (Y, J, H and Ks) over a field of view of ∼400 arcmin2. The typical depth of WUDS data reaches between ∼26.8 in Y and J, and ∼26 in H and Ks (AB, 3σ in 1.3″ aperture), whereas the corresponding depth of the CFHTLS-D3 images in this region ranges between 28.6 and 29 in ugr, 28.2 in i and 27.1 in z (same S/N and aperture). The area and depth of this survey were specifically tailored to set strong constraints on the cosmic star formation rate and the luminosity function brighter or around L⋆ in the z ∼ 6 −...